Half-Life 2 (stylized as HλLF-LIFE2) is a first-person shootervideo game developed and published by Valve Corporation. It is the sequel to 1998's Half-Life, and was released in November 2004 following a five-year, $40 million development phase. During development, a substantial part of the project was leaked and distributed on the Internet. The game was developed alongside Valve's Steam software and the Source engine.

Taking place some years after the events of Half-Life, protagonist Gordon Freeman is awakened by the enigmatic G-Man to find the world has been taken over by the alien Combine. Joined by allies including resistance fighter Alyx Vance, Gordon searches for a way to free humanity using a variety of weapons, including the object-manipulating Gravity Gun.

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A screenshot of the player engaging a group of antlions with a pulse rifle. Along the bottom of the screen, the player's health, suit charge level, and their ammunition are displayed.

Like its predecessor, Half-Life 2 is a single-player first-person shooter broken into several chapters, permanently casting the player as protagonist Gordon Freeman. The sequel has similar mechanics to Half-Life, including health-and-weapon systems and periodic physics puzzles, except with the newer Source engine and improved graphics. The player also starts without items, slowly building up their arsenal over the course of the game. Despite the game's mainly linear nature, much effort was put into making exploration rewarding and interesting; many optional areas can be missed or avoided.

A diverse set of enemies is present, which usually require being approached with different tactics: some coordinate in groups to out-maneuver or out-position the player; others, such as the Manhack, fly directly at the player through small openings and tight corridors. Others use predictable but powerful attacks, while others hide before swiftly attacking the player. Gordon can kill most enemies with his weapons, or make use of indirect means, exploiting environmental hazards such as explosive pressurized canisters, gas fires or improvised traps. For some portions of the game, Gordon can be joined by up to four armed Resistance soldiers or medics, and can send his team further from him or call them back.

Many of the game's new features utilize its detailed physics simulation. Two sections of the game involve driving vehicles. Instead of button-orientated puzzles from Half-Life, environmental puzzles are also introduced with makeshift mechanical systems, revolving around the player's new ability to pick up, move, and place objects. Solutions involve objects' physical properties, such as shape, weight, and buoyancy. For example; In chapter three, "Route Kanal", the player is required to stack cinder blocks on a makeshift see-saw ramp to proceed over a wall. Alternatively, the player can build a crude staircase with the blocks, so the puzzle may be solved in multiple ways.

Part-way through the game, Gordon acquires the Gravity Gun, which allows him to draw distant objects towards himself or forcefully push them away, as well as the ability to manipulate larger and heavier objects that he cannot control without the weapon. These abilities are required to solve puzzles later in the game, and can also be used to great effect in combat, as any non-static object within proximity to the player has the potential to be used as a makeshift defense, such as a file cabinet, or a deadly projectile, such as a gasoline can or buzzsaw blade.

The game never separates the player with pre-rendered cutscenes or events; the story proceeds via exposition from other characters and in-world events, and the player is able to control Gordon for the entirety of the game. Much of the backstory to the game is simply alluded to, or told through the environment.

Some years after Gordon Freeman and other scientists accidentally opened a portal to a dimension of hostile aliens at the Black Mesa Research Facility, Freeman is awoken from stasis by the mysterious G-Man.[1][2] The portal attracted the attention of the Combine, a technologically superior multidimensional empire which conquered Earth in seven hours. The Combine have implemented a brutal police state by biologically assimilating humans and other species, and preventing humans from breeding via a "suppression field". The G-Man inserts Gordon into a train arriving at City 17, site of the Combine Citadel, where Dr. Wallace Breen, the former Black Mesa administrator who negotiated Earth's surrender, governs as the Combine's puppet ruler.[3]

After eluding Combine forces, Gordon joins resistance members including Barney Calhoun, a former Black Mesa security guard working undercover as a Combine police officer; Dr. Eli Vance, former Black Mesa scientist and leader of the resistance; Alyx Vance, Eli's daughter; and Dr. Kleiner, an eccentric Black Mesa scientist. After a failed attempt to teleport to the resistance base, Black Mesa East, from Kleiner's makeshift laboratory, Gordon progresses on foot through the city's canal system. He obtains an airboat and battles his way to Black Mesa East, several miles from the city.[4][5]

Gordon is reintroduced to Eli and meets another resistance scientist, Dr. Judith Mossman.[6] Alyx introduces Gordon to her pet robot D0g and gives him a "gravity gun", an instrument which can manipulate large objects. Black Mesa East comes under Combine attack, and Eli and Mossman are taken to Nova Prospekt, a Combine prison. Separated from Alyx, Gordon detours through the zombie-infested town of Ravenholm, assisted by its last survivor, Father Grigori. Escaping the town, Gordon discovers a resistance outpost, and uses a customized dune buggy to travel a crumbling coastal road to Nova Prospekt, encountering Combine patrols and helping the resistance fend off raids.

Gordon lays siege to Nova Prospekt by using pheromone pods to command the hordes of alien antlions that infest the coast. He reunites with Alyx in the prison and they locate Eli, but discover that Mossman is a Combine informant. Before they can stop her, Mossman teleports herself and Eli back to City 17's Citadel. The Combine teleporter explodes as Gordon and Alyx use it to escape Nova Prospekt.

Returning to Kleiner's lab, Gordon and Alyx learn that the teleporter malfunctioned and that a week has passed. During their absence, the resistance has mobilized against the Combine.[7] In battle, Alyx is captured by the Combine and taken to the Citadel. Gordon fights his way to the Citadel with the aid of D0g and Barney.[8] He is caught in a Combine "confiscation chamber" which destroys all his weapons except the gravity gun, which is inadvertently supercharged by the forcefield, allowing him to pick up Combine soldiers.

Gordon is captured in a Combine transport pod and taken to Breen's office, where he and Mossman are waiting with Eli and Alyx in captivity. Breen explains his plans for further conquest of humanity by the Combine, contrary to what he told Mossman.[9] Angered, Mossman frees Gordon, Alyx, and Eli before Breen can teleport them off-world. Breen tries to escape through a portal, but Gordon destroys the portal reactor with the gravity gun. Just before the Citadel is destroyed in an ensuing explosion, time is frozen. The G-Man reappears, praising Gordon for his actions in City 17. Making vague mention of "offers for [Gordon's] services", the G-Man places him back into stasis.[10]

Many elements were cut from the game. Half-Life 2 was originally intended to be a darker game with grittier art direction, where the Combine were more obviously draining the oceans for minerals and replacing the atmosphere with noxious, murky gases. Nova Prospekt was originally intended to be a small Combine rail depot built on an old prison in the wasteland. Eventually, Nova Prospekt grew from a stopping-off point along the way to the destination itself.[14]

Valve announced Half-Life 2 at E3 in May 2003, where it won several awards for best in show. Originally slated for release in September 2003, the game was delayed in the wake of the cracking of Valve's internal network.[15] The network was accessed through a null session connection to a server owned by Tangis, which was hosted in Valve's network, and a subsequent upload of an ASP shell, resulting in the leak of the game's source code and many other files including maps, models and a playable early version of Half-Life 2 in early September 2003.[16] On October 2, 2003, Valve CEO Gabe Newell publicly explained in the Halflife2.net (now ValveTime.net) forums[17] the events that Valve experienced around the time of the leak, and requested users to track down the perpetrators if possible.

In June 2004, Valve Software announced in a press release that the FBI had arrested several people suspected of involvement in the source code leak.[18] Valve claimed the game had been leaked by a German black-hat hacker named Axel "Ago" Gembe. After the leak, Gembe had contacted Newell through e-mail (also providing an unreleased document planning the E3 events).[19] Newell kept corresponding with Gembe, and Gembe was led into believing that Valve wanted to employ him as an in-house security auditor. He was to be offered a flight to the USA and was to be arrested on arrival by the FBI. When the German government became aware of the plan, Gembe was arrested in Germany instead, and put on trial for the leak as well as other computer crimes in November 2006, such as the creation of Agobot, a highly successful trojan which harvested users' data.[20][21][22]

At the trial in November 2006 in Germany, Gembe was sentenced to two years' probation. In imposing the sentence, the judge took into account such factors as Gembe's difficult childhood and the fact that he was taking steps to improve his situation.[21]

A 1 GB portion of Half-Life 2 became available for pre-load through Steam on August 26, 2004. This meant that customers could begin to download encrypted game files to their computer before the game was released. When the game's release date arrived, customers were able to pay for the game through Steam, unlock the files on their hard drives and play the game immediately, without having to wait for the entire game to download. The pre-load period lasted for several weeks, with several subsequent portions of the game being made available, to ensure all customers had a chance to download the content before the game was released.[23]

Half-Life 2 was simultaneously released through Steam, CD, and on DVD in several editions. Through Steam, Half-Life 2 had three packages that a customer could order. The basic version ("Bronze") includes only Half-Life 2 and Counter-Strike: Source, whereas the "Silver" and "Gold" (collector's edition) versions also include Half-Life: Source (ports of the original Half-Life and Day of Defeat mod to the new engine). The collector's edition/"Gold" version additionally includes merchandise, such as a T-shirt, a strategy guide and CD containing the soundtrack used in Half-Life 2. Both the disc and Steam versions require Steam to be installed and active for play to occur.[24]

A demo version with the file size of a single CD was later made available in December 2004 at the web site of graphics card manufacturer ATI Technologies, who teamed up with Valve for the game. The demo contains a portion of two chapters: Point Insertion and "We Don't Go To Ravenholm...". This demo is currently available on Steam. In September 2005, Electronic Arts distributed the Game of the Year edition of Half-Life 2. Compared to the original CD-release of Half-Life 2, the Game of the Year edition also includes Half-Life: Source.[25]

According to Vivendi Universal Games, the distribution contract they signed with Valve included cyber cafés. This would mean that only Vivendi Universal Games could distribute Half-Life 2 to cyber cafés — not Valve through the Steam system. On November 29, 2004, Judge Thomas S. Zilly, of U.S. Federal District Court in Seattle, Washington, ruled that Vivendi Universal Games and its affiliates are not authorized to distribute (directly or indirectly) Valve games through cyber cafés to end users for pay-to-play activities pursuant to the parties' current publishing agreement. In addition, Judge Zilly ruled in favor of the Valve motion regarding the contractual limitation of liability, allowing Valve to recover copyright damages for any infringement as allowed by law without regard to the publishing agreement's limitation of liability clause.[27]

On April 29, 2005, the two parties announced a settlement agreement. Vivendi Universal Games would cease distributing all retail packaged versions of Valve games by August 31, 2005. Vivendi Universal Games also was to notify distributors and cyber cafés that had been licensed by Vivendi Universal Games that only Valve had the authority to distribute cyber café licenses, and hence their licenses were revoked and switched to Valve's.[28]

On December 22, 2005, Valve released a 64-bit version of the Source game engine for x86-64 processor-based systems running Windows XP Professional x64 Edition, Windows Server 2003 x64, Windows Vista x64, or Windows Server 2008 x64. This update, delivered via Steam, enabled Half-Life 2 and other Source-based games to run natively on 64-bit processors, bypassing the 32-bit compatibility layer. Gabe Newell, one of the founders of Valve, stated that this is "an important step in the evolution of our game content and tools", and that the game benefits greatly from the update.[29] The response to the release varied: some users reported huge performance boosts, while technology site Techgage found several stability issues and no notable frame rate improvement.[30] At the time of release, 64-bit users reported bizarre in-game errors including characters dropping dead, game script files not being pre-cached (i.e., loaded when first requested instead), map rules being bent by AI, and other glitches.[31][32]

Valve partnered with Taito to release Half-Life 2: Survivor, an arcade game version of the game for the Japanese market in 2006.[33][34] During Electronic Arts' summer press event on July 13, 2006, Gabe Newell announced that Half-Life 2 would ship on next-generation consoles (specifically, the Xbox 360 and PlayStation 3) along with episodes One and Two, Team Fortress 2, and Portal[35] in a package called The Orange Box. The Windows version was released on October 10, 2007, as both a retail boxed copy, and as a download available through Valve's Steam service. The Xbox 360 version was also released on October 10, 2007. A PlayStation 3 version was released on December 11, 2007.[36]

On May 26, 2010, Half-Life 2, along with Half-Life 2: Episode One and Episode Two, was released for Mac OS X.[37]Portal was made available for the platform on May 13, 2010, and despite the notable absence of Team Fortress 2 on the platform, Valve began selling The Orange Box for OS X on May 26, 2010. OS X support for Team Fortress 2 was added on June 10, 2010, completing the package.[38] In May 2013, Valve released a beta update to Half-Life 2 which included support for the Oculus Riftvirtual reality headset, with a full release of the feature coming later that year in June.[39]

Purchasers of the Gold Package[42] of the game were given (among other things) a CD soundtrack, titled The Soundtrack of Half-Life 2, containing nearly all the music from the game, along with three bonus tracks. This CD was available for separate purchase via the Valve online store. The soundtrack was re-released in 2014 for use in Steam Music.[43]

Tracks 15, 16, 18 and 42 are bonus tracks that are exclusive to the CD soundtrack. Many of the tracks were retitled and carried over from the Half-Life soundtrack; The names in parentheses are the original titles. Tracks 34, 41, and 42 are remixes. The composer of the soundtrack is Kelly Bailey.[44][45]

In the United States, Half-Life 2's computer version sold 680,000 copies and earned $34.3 million by August 2006. It was the country's 17th best-selling computer game between January 2000 and August 2006.[62] It received a "Platinum" sales award from the Entertainment and Leisure Software Publishers Association (ELSPA),[63] indicating sales of at least 300,000 copies in the United Kingdom.[64]Forbes reported on February 9, 2011 that the game had sold 12 million copies worldwide.[65]

In a review of The Orange Box, IGN stated that although Half-Life 2 has already been released through other mediums, the game itself is still enjoyable on a console. They also noted that the physics of Half-Life 2 are very impressive despite being a console title. However, it was noted that the graphics on the Xbox 360 version of Half-Life 2 were not as impressive as when the title was released on the PC.[66] GameSpot's review of The Orange Box noticed that the content of both the Xbox 360 releases, and PlayStation 3 releases were exactly alike, the only issue with the PlayStation 3 version was that it had noticeable frame-rate hiccups. GameSpot continued to say that the frame rates issues were only minor but some consider them to be a significant irritation.[53]

Several critics, including some that had given positive reviews, complained about the required usage of the program Steam, the requirement to create an account, register the products, and permanently lock them to the account before being allowed to play, along with installation difficulties and lack of support.[61]

The editors of Computer Gaming World nominated Half-Life 2 for their 2004 "Single-Player Shooter of the Year" and overall "Game of the Year" awards, although it lost to Painkiller and World of Warcraft, respectively. They wrote, ""Half-Life 2, everyone's default pick to win this year, is indeed a fantastic roller coaster of a ride, not as great as the original but still leagues above most other shooters."[67]

Half-Life 2 earned 39 Game of the Year awards,[68] including Overall Game of the Year at IGN, GameSpot's Award for Best Shooter, GameSpot's Reader's Choice — PC Game of the Year Award, Game of the Year from The Academy of Interactive Arts & Sciences, and "Best Game" with the Game Developers Choice Awards, where it was also given various awards for technology, characters, and writing. Edge magazine awarded Half Life 2 with its top honor of the year with the award for Best Game, as well as awards for Innovation and Visual Design. The game also had a strong showing at the 2004 British Academy Video Games Awards, picking up six awards, more than any other game that night, with awards including "Best Game" and "Best Online and Multiplayer."[69]Computer Games Magazine named Half-Life 2 the fourth-best computer game of 2004. The editors call it "a masterful single-player experience that plays a constant game of one-upmanship with itself." It won the magazine's "Best Technology" and "Best Writing" awards, and was a runner-up in the "Best Sound Effects", "Best AI" and "Best Voice Acting" categories.[70]

Guinness World Records awarded Half-Life 2 the world record for "Highest Rated Shooter by PC Gamer Magazine" in the Guinness World Records: Gamer's Edition 2008. Other records awarded the game in the book include, "Largest Digital Distribution Channel" for Valve's Steam service, "First Game to Feature a Gravity Gun", and "First PC Game to Feature Developer Commentary".[71] In 2009, Game Informer put Half-Life 2 5th on their list of "The Top 200 Games of All Time", saying that "With Half-Life 2, Valve redefined the way first-person shooters were created".[72]

Half-Life 2 was selected by readers of The Guardian as the best game of the decade, with praise given especially to the environment design throughout the game. According to the newspaper, it "pushed the envelope for the genre, and set a new high watermark for FPS narrative". One author commented: "Half-Life 2 always felt like the European arthouse answer to the Hollywood bluster of Halo and Call of Duty".[73]Half-Life 2 won Crispy Gamer's Game of the Decade[74] tournament style poll. It also won Reviews on the Run's,[75] IGN's[76] Best Game of the Decade and Spike Video Game Awards 2012 Game of the Decade.[77]

Since the release of the Source engine SDK, a large number of modifications (mods) have been developed by the Half-Life 2 community. Mods vary in scale, from fan-created levels and weapons, to partial conversions such as Rock 24, Half-Life 2 Substance and SMOD (which modify the storyline and gameplay of the pre-existing game), SourceForts and Garry's Mod (which allow the player to experiment with the physics system in a sandbox mode), to total conversions such as Black Mesa, Dystopia, Zombie Master or Iron Grip: The Oppression, the last of which transforms the game from a first-person shooter into a real-time strategy game.[78][79] Some mods take place in the Half-Life universe; others in completely original settings. Many more mods are still in development, including Lift, The Myriad, Operation Black Mesa, and the episodic single-player mod Minerva.[80] Several multiplayer mods, such as Pirates, Vikings and Knights II, a predominately sword-fighting game; Insurgency: Modern Infantry Combat, which focuses on realistic modern infantry combat; and Jailbreak Source have been opened to the public as a beta.[81][82] As part of its community support, Valve announced in September 2008 that several mods, with more planned in the future, were being integrated into the Steamworks program, allowing the mods to make full use of Steam's distribution and update capabilities.[83]

Since the release of Half-Life 2, Valve Corporation has released an additional level and two additional "expansion" sequels. The level, released as Half-Life 2: Lost Coast, was meant to take place between the levels "Highway 17" and "Sandtraps".[84] It serves primarily as a showcase for high-dynamic-range rendering (HDR) technology. The first expansion sequel, Half-Life 2: Episode One, takes place immediately after the events of Half-Life 2, with the player taking on the role of Gordon Freeman once again and with Alyx Vance playing a more prominent role. Half-Life 2: Episode Two continues directly from the ending of Episode One, with Alyx and Gordon making their way to White Forest Missile base, a hideout of the resistance. A third episode is set to be released in the future, completing a trilogy.[85] In a June 2006 interview with Eurogamer, Gabe Newell revealed that the Half-Life 2 "episodes" are essentially Half-Life 3.[86] He reasons that rather than force fans to wait another six years for a full sequel, Valve Corporation would release the game in episodic installments.[86] Newell stated that a more accurate title for these episodes would have been "Half-Life 3: Episode One" and so forth, having referred to the episodes as Half-Life 3 repeatedly throughout the interview.[86] In a May 2011 interview with Develop, Newell stated that the episodic model had been replaced by even shorter development cycles and continuous updates via Steam.[87]

^Valve Corporation (2004-11-16). Half-Life 2. Microsoft Windows, Xbox, Xbox 360, PlayStation 3, Mac OS X. Valve Corporation, Sierra Entertainment. Level/area: Chapter 1: Point Insertion. The G-Man: [at the start of the game, over a psychedelic series of images calling back toHalf-Lifeand forward to the final chapters] Rise and shine, Mr. Freeman. Rise and...shine. Not that I wish...to imply that you have been sleeping on...the job. No one is more deserving of a rest, and all the effort in the world would have gone to waste until...well...let's just say your hour has come again. [...] The right man in the wrong place can make all the difference...in the world. So, wake up, Mr. Freeman. Wake up and...smell the ashes...

^Valve Corporation (2004-11-16). Half-Life 2. Microsoft Windows, Xbox, Xbox 360, PlayStation 3, Mac OS X. Valve Corporation, Sierra Entertainment. Level/area: Chapter 2: "A Red Letter Day". Barney: Hey, Gordon! The Citadel's on full alert, I've never seen it lit up like that! Get out of City 17 as fast as you can, Gordon! Take the old canals, right? They'll take you to Eli's place. It's a dangerous route, bu there's a whole network of refugees, and they'll help you if they can. I'd come with you, but I've gotta look after Doctor Kleiner. Oh, and before I forget—[picks up a crowbar]—I think you dropped this back at Black Mesa! [drops the crowbar to Gordon] Good luck out there, buddy! You're gonna need it.

^Valve Corporation (2004-11-16). Half-Life 2. Microsoft Windows, Xbox, Xbox 360, PlayStation 3, Mac OS X. Valve Corporation, Sierra Entertainment. Level/area: Chapter 13: Dark Energy. G-Man: Time, Doctor Freeman? Is it really that...time again? It seems as if you only just arrived. ["walks out" from the explosion] You have done a great deal in a small time...span. You've done so well, in fact, that I've received some interesting offers for your services. Ordinarily, I wouldn't contemplate them, but these are extra...ordinary times. Rather than offer you the illusion of free choice [like last time], I will take the liberty of choosing for you...if and when your time comes around again. / [The G-Man extracts Gordon from the Citadel and re-enters the "black void" from the beginning of the game.] / G-Man: I...do apologize for what must seem to you an "arbitrary imposition", Dr. Freeman. I trust it will all make sense to you in the course of...well, I'm really not at liberty to say. In the meantime...this is where I get off.[smiles, then walks away]